Tulsa police said Shelby had not been subject to any disciplinary proceedings in her 5 years on the force

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In this file image from a Sept. 16, 2016 police video, Terence Crutcher, left, is pursued by police in Tulsa, Okla. Crutcher was fatally shot by one of the officers.

The Tulsa police officer accused of manslaughter in the fatal shooting of an unarmed black man took a roundabout path toward her dream job of joining law enforcement, with stops as a convenience store clerk, an Air National Guard member and a teaching assistant.

Family members and colleagues say Betty Jo Shelby, 42, was an engaged community member, a churchgoer and cool-headed enough to be tapped as a field-training officer even though she didn't join the Tulsa County Sheriff's Office until 2007 and the city's force until 2011.

Despite completing de-escalation training, Shelby "reacted unreasonably" when she fatally shot 40-year-old Terence Crutcher on Sept. 16, according to an affidavit prosecutors filed with the first-degree murder charge. Shelby, who posted bond early Friday, faces four years to life in prison if convicted.

Shelby's attorney, Scott Wood, said Friday that she had a reputation of having a "cool head on her shoulders."

"This wasn't her first week on the job," Wood said. "Betty is a field-training officer. The department has picked her to train new officers, and people will tell you this isn't Betty Shelby to overreact to a situation."

Shelby, who is white, was headed to a domestic violence call when she encountered Crutcher's SUV abandoned on a city street, straddling the center line. Shelby did not activate her dashboard camera when she first came across Crutcher and his SUV. But other video footage shows Crutcher walking away from Shelby and toward his SUV with his arms in the air. The footage does not offer a clear view of when Shelby fired the single shot that killed Crutcher.

Wood said Crutcher escalated the situation by not communicating with Shelby, disobeying her commands and walking away from her. "One thing about de-escalation, that's a two-way street," Wood said. "You have to at least have some open communication. There was none with Mr. Crutcher."

Mark Sawa, a retired major with the Travis County Sheriff's Office in Austin, Texas, who trains police officers on use of force, said: "If somebody is not contained, if they're walking away from you, your opportunity to defuse that encounter is greatly diminished if they're mobile and not stationary."

He cautioned that he couldn't fully assess how the situation got out of hand, as no video is available until after Shelby already has her gun drawn and Crutcher is walking away from her with his hands in the air.

Crutcher died of a gunshot wound to the chest, the state medical examiner's office said Friday, adding that the full autopsy and toxicology reports were not finished. His funeral is scheduled for Saturday.

Shelby joined the Tulsa County Sheriff's Office in 2007 and stayed until 2011, resigning with a salary of $39,516. Records show one "use-of-force" report in 2010, drawing but not firing a gun while searching for a suspect.

Her Sheriff's Office application shows she said she smoked marijuana twice as a teenager and had two protective orders taken out against her — once when she was about 20 after a breakup when she and her ex-boyfriend took a shovel to each other's cars in anger. The second incident in 2000 followed one of Shelby's two divorces; she alleges her ex-husband's new wife sought a protective order "in an attempt to discredit my character." In both cases, Shelby said a judge agreed to dismiss the orders.

Shelby joined the Tulsa Police Department in December 2011; her husband David works there, too. Her salary was $53,747 as of May 31, according to a city spokeswoman; she was placed on leave without pay Friday.

The department refused the AP's repeated requests to release her personnel records, but said the officer has not been subject to any disciplinary proceedings in her nearly five years.

She has garnered accolades due to her work in the community, said Sgt. Patrick Stephens, a spokesman with the Tulsa Fraternal Order of Police Lodge 93, of which Shelby is a member. On Aug. 28, she was featured in a Tulsa Police Department Facebook post after she located and returned property stolen from two residents; there's a photo of her posing with the pair, who brought her a bouquet of flowers.

Shelby's pastor, Benjamin Williams of the Glenpool Church of Christ in suburban Tulsa, described her as quiet, reserved and someone who "doesn't fit the stereotype" of an extrovert police officer.